From Wikipedia, the free encyclopedia

The Patapsco is a river in central Maryland which flows into the Chesapeake Bay in Baltimore, Maryland. With its South Branch, it forms the northern border of Howard County, Maryland.

Contents 1 Geography 2 History 3 References 4 Further reading

The Patapsco proper begins at the confluence of the North and South Branches, near Marriottsville, approximately 50 miles inland. The South Branch rises further west at Parrs Spring, where Howard, Carroll, Frederick, and Montgomery counties meet. The North Branch flows southward from its origins in Carroll County. Through most of its length, the Patapsco is a minor river, flowing for the most part through a narrow valley. The last 10 miles form a large tidal estuary inlet of Chesapeake Bay. The inner part of this estuary provides the harbor of Baltimore, composed of the Northwest Harbor and the Middle Branch. (See Baltimore Inner Harbor.)

The Patapsco has a watershed area (including the water surface) of 680 square miles, or 632 square miles of land. Thus, its total watershed area is 7% water.

Patapsco Valley State Park is adjacent to 32 miles of the Patapsco, encompassing a total of 14,000 acres (57 km²) in five different areas. Liberty Dam and its reservoir, located on the north fork, is a major component of the Baltimore city water system. Besides Baltimore, the river also flows through Ellicott City (the county seat of Howard County) and Elkridge.

On the 1612 John Smith map, it was called the Bolus River. It has never been a major path of commerce since it is not navigable further upstream than Elkridge. However, the Patapsco valley was used as the route of the Baltimore and Ohio Railroad's original main line west constructed from 1829 onwards (see Old Main Line (Baltimore and Ohio Railroad)), and this route remains, though much altered. Many old rail bridges lie along the valley, most notably the Thomas Viaduct and the ruins of the Patterson Viaduct. Flour mills and a hydropower dam were formerly powered by the river.

The valley is prone to flooding, though at long intervals. The most recent severe flood occurred in 1972 as a result of rainfall from the remnants of Hurricane Agnes, in which Ellicott City and the B&O rail line sustained serious damage.

The Patapsco River is home to the Baltimore Rowing Club.

• Chesapeake Bay Program Watershed Profile: Patapsco/Back River
• Patapsco Valley State Park

• Maryland DNR's Surf Your Watershed: Patapsco/Back River
• Maryland Port Administration
• Patapsco Riverkeeper